·Netonatal uterus- Average size: length 3.4 cm width 1.25 cm.
NB The fetus is subject to the influence of maternal hormones and thus at birth the neonatal uterus has a similar configuration to the postpubertal uterus. The uterus involutes over the next few weeks. Intracavitary fluid is a common normal finding.
·Prepubertal uterus- Average size: length 2—3.3 cm width 0.5—1 cm.
NB At this stage the body and cervix of the uterus are of similar length, giving a body:cervix ratio of 1:1. After puberty the ratio increases to 2:1.
·Puberty- Average size: length 5—8 cm width 1.6—3 cm.
·Uterine volume- Approximately length x width x breadth x 0.5.
Prepubertal: <2 ml.
Puberty: 25 ml.
·Pregnancy-During pregnancy the uterus increases in size up to 30 times by muscle hypertrophY. After pregnancy it involutes but usually remains larger than before.
·Uterine hypoplasia-Not usually evident until puberty. Causes include lack of estrogens chromosomal anomalies and in utero exposure to diethylestilbestrol.